Differential FAK phosphorylation at Ser-910, Ser-843 and Tyr-397 induced by angiotensin II, LPA and EGF in intestinal epithelial cells

Abstract

A rapid increase in the tyrosine phosphorylation of the non-receptor tyrosine kinase FAK is a prominent early event in fibroblasts stimulated by a variety of signaling molecules. However, a variety of epithelial cells, including intestinal epithelial cells, show a high basal level of tyrosine phosphorylated FAK that is only slightly further increased by addition of G protein-coupled receptors (GPCR) agonists or growth factors. In this study, we determined whether these stimuli could elicit FAK phosphorylation at serine residues, including Ser-910 and Ser-843. Our results show that multiple agonists including angiotensin II (ANGII), lysophosphatidic acid (LPA), phorbol esters and EGF induced a striking stimulation of FAK phosphorylation at Ser-910 in rat intestinal epithelial IEC-18 cells via an ERK-dependent pathway. In striking contrast, none of these stimuli promoted a significant further increase in FAK phosphorylation at Tyr-397 in these cells. These results were extended using cultures of polarized human colonic epithelial T84 cells. We found that either carbachol or EGF promoted a striking ERK-dependent phosphorylation of FAK at Ser-910, but these agonists caused only slight stimulation of FAK at Tyr-397 in T84 cells. In addition, we demonstrated that GPCR agonists also induced a dramatic increase of FAK phosphorylation at Ser-843 in either IEC-18 or T84 cells. Our results indicate that Ser-910 and Ser-843, rather than Tyr-397, are prominent sites differentially phosphorylated in response to neurotransmitters, bioactive lipids, tumor promoters and growth factors in intestinal epithelial cells.

GABABReceptor Activation Protects Neurons from Apoptosis via IGF-1 Receptor Transactivation

“…Recently, a large body of evidence suggested that a rapid increase of the tyrosine phosphorylation for a nonreceptor tyrosine kinase, FAK, is a common response to multiple GPCR agonists (Rozengurt, 2002). Interestingly, whereas /calmodulin-dependent protein kinase II (CaMKII), indicating that FAK is a point of integration of tyrosine and serine phosphorylation (Fan et al, 2005;Jacamo et al, 2007;Jiang et al, 2007). Our results showed that Ca 2ϩ signaling and FAK1 are involved in GABA B receptor-IGF-1R transactivation, suggesting that GABA B receptor-mediated Ca 2ϩ signaling may induce phosphorylation of FAK at Ser 843 , which in turn induces FAK tyrosine kinase activity and downstream signaling.…”

P21-activated protein kinase 1 induces colorectal cancer metastasis involving ERK activation and phosphorylation of FAK at Ser-910

“…In CRC samples, the Ser-910-phosphorylated FAK was also elevated with development of tumor stages. Ser-843, the other serine residue of FAK, has also been reported to be phosphorylated in epithelial cells through a Ca 2+ -dependent manner (26). The elucidation of the precise role of FAK phosphorylation at Ser-843 in epithelial cells warrants further study.…”

“…Recent studies showed that EGF induces FAK phosphorylation at Ser-910 through an ERK-dependent pathway, inhibiting the ability of FAK to associate with paxillin and formation of focal adhesion complex (21,26). The reduced formation of focal adhesion contact is helpful for cell migration (20).…”

Conformational Dynamics of the Focal Adhesion Targeting Domain Control Specific Functions of Focal Adhesion Kinase in Cells

“…Enhanced Tyr 861 phosphorylation may be a direct structural consequence of altered conformational FAT dynamics and/or it may result indirectly from increased Tyr 925 phosphorylation, as the latter has been reported to influence Tyr 861 phosphorylation (50). FAK is also phosphorylated on several serine residues (44, 52) that regulate cell spreading and migration (53). The major such site in the C-terminal region of FAK is Ser 910 , a substrate of ERK (45).…”